This disclosure relates generally to television receivers, and is particularly directed to means for attaching the backs of television receiver cabinets.
A television receiver commonly consists of a cabinet made of wood, metal or a plastic having an open back for access to the components. The largest of these components is the cathode ray picture tube which has a substantially rectangular face panel with a rearwardly extending flange attached to a funnel portion and a neck portion oriented on the axis of the tube. The electronic section of the receiver is typically subdivided into parts placed at convenient locations beneath and at the sides of a cathode ray tube. The open back is normally covered by a panel that restricts access to the components.
Access is restricted to prevent the entry into the cabinet by unauthorized persons who may suffer injury because of the 117 volt AC potential located at various points on the electrical chassis, and the very high voltage in the range of 25-30 kilovolts applied to the cathode ray tube for establishing the anode potential. However, while denying entry to unauthorized persons, the covering panel must be easily and quickly removable by service technicians. Also, easy access by authorized persons must be facilitated during manufacture as it is often necessary to install and remove the back several times to make final adjustments.
Another requirement is that the panel that covers the back must be securely attached and able to resist dislodging forces experienced during handling and shipping. That these forces are considerable is shown by the fact that a television receiver can experience shocks of the magnitude of 30 g's during shipment.
A further requirement is that the attachment must be firm; otherwise, the panel may rattle in response to the vibration originating in the loudspeaker cones. Sympathetic vibration of back panel members can be very annoying to television receiver users.
Other requirements include the need for design simplicity so that the parts are relatively inexpensive to manufacture. Finally, the back should be removable without the need for special tools.
Pabich in U.S. Pat. No. 3,768,064 discloses a safety back for an appliance cabinet, such as a TV cabinet. According to Pabich, the appliance cabinet cannot be opened without following a procedure involving several steps in predetermined sequence and, in some cases, without having a special tool. The object is to provide a cabinet back which cannot be removed by small children or incompetent persons who might be injured by electrical shock if they put their hands inside the cabinet. In one embodiment, the back panel of the cabinet has means for precluding release of the panel from the cabinet unless the panel is first slipped to a release position, and a mechanical interlock means for preventing slippage of the panel. The mechanical interlock may comprise a socket on a power cord or ones of several types of fasteners having different slot configurations.